Research and application of a power-flow-calculation method in multiterminal VSC-HVDC power grid

• Main Authors: Linlin Wu, Xiaowei Fan, Man Xu, Zhendong Li, Xiao Wang, Xiaofei Zhang, Haiwang Jin
• Format: Article
• Language: English
• Published: KeAi Communications Co., Ltd. 2019-02-01
• Series: Global Energy Interconnection
• Online Access: http://www.sciencedirect.com/science/article/pii/S2096511719300258

For demonstrating a multiterminal voltage-source converter (VSC)-based high-voltage DC (HVDC) (VSC- HVDC) project, this study puts forward a technical route for calculating the power flow in a 500-kV VSC-HVDC power grid in comparison with that of an AC power grid. The Jacobian matrix used in the power-flow calculation was deduced through methods such as Newton-Laphson iteration and Taylor series expansion. Further, the operation effect of power- flow calculation on a true bipolar VSC-HVDC power grid was analyzed briefly. The elements of the Jacobian matrix corresponding to VSC were studied under the mode of droop control and the control strategy of VSC-HVDC power grid was analyzed in detail. The power-flow calculation model for VSC-HVDC power grid of the master-slave control mode was simplified using the PQ decomposition method of the power-flow calculation of an AC power grid. Moreover, a four-terminal model of the Zhangbei VSC-HVDC demonstration project was established and tested on MATLAB. The simulation results under two kinds of operating conditions were analyzed and compared to the results of BPA; the deviation between the power-flow results was studied. The results show that the proposed calculation method can provide a feasible support for calculating the power flow in VSC-HVDC grids. Keywords: VSC-HVDC grids, Power-flow calculation, Jacobian matrix, Droop control